Does anyone know of a possible way to put retracts on ultra micro aircrafts like the parkzone ultra micros? (Spitfire, p-51, corsair, etc...)
I've been thinking of a way to do it but I'm not sure if it will work and be light enough.
Depending on just how "ultra micro" you refer to, Mr. Newell might have a few good ideas, he has some awesome planes including an 8-channel 1:96 scale P-51 with retracts, and he is active on RC Groups too if you can't find some ideas from his YouTube channels.
Keep in mind this kind of construction is the product of a master craftsman performing a the top of their game. They may do better/smaller, but just this alone makes them among the best in that nitch. Mere mortals may be able to do the same, but not without spending the time (think years) building and honing the skills needed.
That being said, it doesn't take that much of an increase in size to see required the skill level drop to a very approachable level. All depends on what a person chooses to focus their time on . . .